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  • richardmitnick 9:48 am on March 20, 2017 Permalink | Reply
    Tags: , , Crystallites, Disorder can be good, MIT, , Pyrolysis, Vickers hardness test   

    From MIT: “Disorder can be good” 

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    March 17, 2017
    Denis Paiste

    1
    MIT aerospace researchers have demonstrated that some randomness in the arrangement of carbon atoms makes materials that are lighter and stronger, shown at lower right in illustration, compared to a more densely packed and tightly ordered structure, shown lower left. They formed a type of disordered graphite-like carbon material that is often called glassy carbon by “baking” a phenol-formadehyde hydrocarbon precursor at high temperature in inert gas, a process commonly known as pyrolysis. Illustration: Itai Stein

    Researchers discover that chaos makes carbon materials lighter and stronger.

    In the quest for more efficient vehicles, engineers are using harder and lower-density carbon materials, such as carbon fibers, which can be manufactured sustainably by “baking” naturally occurring soft hydrocarbons in the absence of oxygen. However, the optimal “baking” temperature for these hardened, charcoal-like carbon materials remained a mystery since the 1950s when British scientist Rosalind Franklin, who is perhaps better known for providing critical evidence of DNA’s double helix structure, discovered how the carbon atoms in sugar, coal, and similar hydrocarbons, react to temperatures approaching 3,000 degrees Celsius (5,432 degrees Fahrenheit) in oxygen-free processing. Confusion over whether disorder makes these graphite-like materials stronger, or weaker, prevented identifying the ideal “baking” temperature for more than 40 years.

    Fewer, more chaotically arranged carbon atoms produce higher-strength materials, MIT researchers report in the journal Carbon. They find a tangible link between the random ordering of carbon atoms within a phenol-formaldehyde resin, which was “baked” at high temperatures, and the strength and density of the resulting graphite-like carbon material. Phenol-formaldehyde resin is a hydrocarbon commonly known as “SU-8” in the electronics industry. Additionally, by comparing the performance of the “baked” carbon material, the MIT researchers identified a “sweet spot” manufacturing temperature: 1,000 C (1,832 F).

    “These materials we’re working with, which are commonly found in SU-8 and other hydrocarbons that can be hardened using ultraviolet [UV] light, are really promising for making strong and light lattices of beams and struts on the nanoscale, which only recently became possible due to advances in 3-D printing,” says MIT postdoc Itai Stein SM ’13, PhD ’16. “But up to now, nobody really knew what happens when you’re changing the manufacturing temperature, that is, how the structure affects the properties. There was a lot of work on structure and a lot of work on properties, but there was no connection between the two. … We hope that our study will help to shed some light on the governing physical mechanisms that are at play.”

    Stein, who is the lead author of the paper published in Carbon, led a team under professor of aeronautics and astronautics Brian L. Wardle, consisting of MIT junior Chlöe V. Sackier, alumni Mackenzie E. Devoe ’15 and Hanna M. Vincent ’14, and undergraduate Summer Scholars Alexander J. Constable and Naomi Morales-Medina.

    “Our investigations into this carbon material as a matrix for nanocomposites kept leading to more questions making this topic increasingly interesting in and of itself. Through a series of contributions, notably from MIT undergraduate researchers and Summer Scholars, a sustained investigation of several years resulted, allowing some paradoxical results in the extant literature to be resolved,” Wardle says.

    By “baking” the resin at high temperature in inert gas, a process commonly known as pyrolysis, the researchers formed a type of disordered graphite-like carbon material that is often called glassy carbon. Stein and Wardle showed that when it is processed at temperatures higher than 1,000 C, the material becomes more ordered but weaker. They estimated the strength of their glassy carbon by applying a local force and measuring their material’s ability to resist deformation. This type of measurement, which is known to engineers as the Vickers hardness test, is a highly versatile technique that can be used to study a wide variety of materials, such as metals, glasses, and plastics, and enabled the researchers to compare their findings to many well-known engineering materials that include diamond, carbon fiber composites, and metal carbides.

    The carbon atoms within the MIT researchers’ material were more chaotically organized than is typical for graphite, and this was because phenol-formaldehyde with which they started is a complicated mix of carbon-rich compounds. “Because the hydrocarbon was disordered to begin with, a lot of the disorder remains in your crystallites, at least at this temperature,” Stein explains. In fact, the presence of more complex carbon compounds in the material strengthens it by leading to three-dimensional connections that are hard to break. “Basically you get pinned at the crystallite interface, and that leads to enhanced performance,” he says.

    These high-temperature baked materials have only one carbon atom in their structure for every three in a diamond structure. “When you’re using these materials to make nanolattices, you can make the overall lattice even less dense. Future studies should be able to show how to make lighter and cheaper materials,” Stein suggests. Hydrocarbons similar to the phenol-formaldehyde studied here can also be sourced in an environmentally friendly way, he says.

    “Up until now there wasn’t really consensus about whether having a low density was good or bad, and we’re showing in this work, that having a low density is actually good,” Stein says. That’s because low density in these crystallites means more molecular connections in three dimensions, which helps the material resist shearing, or sliding apart. Because of its low density, this material compares favorably to diamond and boron nitrides for aerospace uses. “Essentially, you can use a lot more of this material and still end up saving weight overall,” Stein says.

    “This study represents sound materials science — connecting all three facets of synthesis, structure, and property — toward elucidating poorly understood scaling laws for mechanical performance of pyrolytic carbon,” says Eric Meshot, a staff scientist at Lawrence Livermore National Laboratory, who was not involved in this research. “It is remarkable that by employing routinely available characterization tools, the researchers pieced together both the molecular and nanoscale structural pictures and deciphered this counterintuitive result that more graphitization does not necessarily equal a harder material. It is an intriguing concept in and of itself that a little structural disorder can enhance the hardness.”

    “Their structural characterization proves how and why they achieve high hardness at relatively low synthesis temperatures,” Meshot adds. “This could be impactful for industries seeking to scale up production of these types of materials since heating is a seriously costly step.” The study also points to new directions for making low-density composite structures with truly transformative properties, he suggests. “For example, by incorporating the starting SU-8 resin in, on, or around other structures (such as nanotubes as the authors suggest), can we synthesize materials that are even harder or more resistant to sheer? Or composites that possibly embed additional functionality, such as sensing?” Meshot asks.

    The new research has particular relevance now because a group of German researchers showed last year in a Nature Materials paper how these materials can form highly structured nanolattices that are strong, lightweight, and are outperformed only by diamond. Those researchers processed their material at 900 C, Stein notes. “You can do a lot more optimization, knowing what the scaling is of the mechanical properties with the structure, then you can go ahead and tune the structure accordingly, and that’s where we believe there is broad implication for our work in this study,” he says.

    This work was partly supported by MIT’s Nano-Engineered Composite aerospace STructures (NECST) Consortium members Airbus Group, Boeing, Embraer, Lockheed Martin, Saab AB, ANSYS, Hexcel, and TohoTenax. Stein was supported, in part, by a National Defense Science and Engineering Graduate Fellowship.

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  • richardmitnick 4:35 pm on March 17, 2017 Permalink | Reply
    Tags: , , MIT, , Scientists make microscopes from droplets, Tunable microlenses   

    From MIT: “Scientists make microscopes from droplets” 

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    March 10, 2017
    Jennifer Chu

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    Researchers at MIT have devised tiny “microlenses” from complex liquid droplets, such as these pictured here, that are comparable in size to the width of a human hair. Courtesy of the researchers

    With chemistry and light, researchers can tune the focus of tiny beads of liquid.

    Liquid droplets are natural magnifiers. Look inside a single drop of water, and you are likely to see a reflection of the world around you, close up and distended as you’d see in a crystal ball.

    Researchers at MIT have now devised tiny “microlenses” from complex liquid droplets comparable in size to the width of a human hair. They report the advance this week in the journal Nature Communications.

    Each droplet consists of an emulsion, or combination of two liquids, one encapsulated in the other, similar to a bead of oil within a drop of water. Even in their simple form, these droplets can magnify and produce images of surrounding objects. But now the researchers can also reconfigure the properties of each droplet to adjust the way they filter and scatter light, similar to adjusting the focus on a microscope.

    The scientists used a combination of chemistry and light to precisely shape the curvature of the interface between the internal bead and the surrounding droplet. This interface acts as a kind of internal lens, comparable to the compounded lens elements in microscopes.

    “We have shown fluids are very versatile optically,” says Mathias Kolle, the Brit and Alex d’Arbeloff Career Development Assistant Professor in MIT’s Department of Mechanical Engineering. “We can create complex geometries that form lenses, and these lenses can be tuned optically. When you have a tunable microlens, you can dream up all sorts of applications.”

    For instance, Kolle says, tunable microlenses might be used as liquid pixels in a three-dimensional display, directing light to precisely determined angles and projecting images that change depending on the angle from which they are observed. He also envisions pocket-sized microscopes that could take a sample of blood and pass it over an array of tiny droplets. The droplets would capture images from varying perspectives that could be used to recover a three-dimensional image of individual blood cells.

    “We hope that we can use the imaging capacity of lenses on the microscale combined with the dynamically adjustable optical characteristics of complex fluid-based microlenses to do imaging in a way people have not done yet,” Kolle says.

    Kolle’s MIT co-authors are graduate student and lead author Sara Nagelberg, former postdoc Lauren Zarzar, junior Natalie Nicolas, former postdoc Julia Kalow, research affiliate Vishnu Sresht, professor of chemical engineering Daniel Blankschtein, professor of mechanical engineering George Barbastathis, and John D. MacArthur Professor of Chemistry Timothy Swager. Moritz Kreysing and Kaushikaram Subramanian of the Max Planck Institute of Molecular Cell Biology and Genetics are also co-authors.

    Shaping a curve

    The group’s work builds on research by Swager’s team, which in 2015 reported a new way to make and reconfigure complex emulsions. In particular, the team developed a simple technique to make and control the size and configuration of double emulsions, such as water that was suspended in oil, then suspended again in water. Kolle and his colleagues used the same techniques to make their liquid lenses.

    They first chose two transparent fluids, one with a higher refractive index (a property that relates to the speed at which light travels through a medium), and the other with a lower refractive index. The contrast between the two refractive indices can contribute to a droplet’s focusing power. The researchers poured the fluids into a vial, heated them to a temperature at which the fluids would mix, then added a water-surfactant solution. When the liquids were mixed rapidly, tiny emulsion droplets formed. As the mixture cooled, the fluids in each of the droplets separated, resulting in droplets within droplets.

    To manipulate the droplets’ optical properties, the researchers added certain concentrations and ratios of various surfactants — chemical compounds that lower the interfacial tension between two liquids. In this case, one of the surfactants the team chose was a light-sensitive molecule. When exposed to ultraviolet light this molecule changes its shape, which modifies the tension at the droplet-water interfaces and the droplet’s focusing power. This effect can be reversed by exposure to blue light.

    “We can change focal length, for example, and we can decide where an image is picked up from, or where a laser beam focuses to,” Kolle says. “In terms of light guiding, propagation, and tailoring of light flow, it’s really a good tool.”

    Optics on the horizon

    Kolle and his colleagues tested the properties of the microlenses through a number of experiments, including one in which they poured droplets into a shallow plate, placed under a stencil, or “photomask,” with a cutout of a smiley face. When they turned on an overhead UV lamp, the light filtered through the holes in the photomask, activating the surfactants in the droplets underneath. Those droplets, in turn, switched from their original, flat interface, to a more curved one, which strongly scattered light, thereby generating a dark pattern in the plate that resembled the photomask’s smiley face.

    The researchers also describe their idea for how the microlenses might be used as pocket-sized microscopes. They propose forming a microfluidic device with a layer of microlenses, each of which could capture an image of a tiny object flowing past, such as a blood cell. Each image would be captured from a different perspective, ultimately allowing recovery of information about the object’s three-dimensional shape.

    “The whole system could be the size of your phone or wallet,” Kolle says. “If you put some electronics around it, you have a microscope where you can flow blood cells or other cells through and visualize them in 3-D.”

    He also envisions screens, layered with microlenses, that are designed to refract light into specific directions.

    “Can we project information to one part of a crowd and different information to another part of crowd in a stadium?” Kolle says. “These kinds of optics are challenging, but possible.”

    This research was supported, in part, by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, and the Max Planck Society.

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  • richardmitnick 10:26 am on March 16, 2017 Permalink | Reply
    Tags: , , , , , MIT   

    From MIT: “Scientists identify a black hole choking on stardust” 

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    March 14, 2017
    Jennifer Chu

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    In this artist’s rendering, a thick accretion disk has formed around a supermassive black hole following the tidal disruption of a star that wandered too close. Stellar debris has fallen toward the black hole and collected into a thick chaotic disk of hot gas. Flashes of X-ray light near the center of the disk result in light echoes that allow astronomers to map the structure of the funnel-like flow, revealing for the first time strong gravity effects around a normally quiescent black hole.
    Image: NASA/Swift/Aurore Simonnet, Sonoma State University

    Data suggest black holes swallow stellar debris in bursts.

    In the center of a distant galaxy, almost 300 million light years from Earth, scientists have discovered a supermassive black hole that is “choking” on a sudden influx of stellar debris.

    In a paper published today in Astrophysical Journal Letters, researchers from MIT, NASA’s Goddard Space Flight Center, and elsewhere report on a “tidal disruption flare” — a dramatic burst of electromagnetic activity that occurs when a black hole obliterates a nearby star. The flare was first discovered on Nov. 11, 2014, and scientists have since trained a variety of telescopes on the event to learn more about how black holes grow and evolve.

    The MIT-led team looked through data collected by two different telescopes and identified a curious pattern in the energy emitted by the flare: As the obliterated star’s dust fell into the black hole, the researchers observed small fluctuations in the optical and ultraviolet (UV) bands of the electromagnetic spectrum. This very same pattern repeated itself 32 days later, this time in the X-ray band.

    The researchers used simulations of the event performed by others to infer that such energy “echoes” were produced from the following scenario: As a star migrated close to the black hole, it was quickly ripped apart by the black hole’s gravitational energy. The resulting stellar debris, swirling ever closer to the black hole, collided with itself, giving off bursts of optical and UV light at the collision sites. As it was pulled further in, the colliding debris heated up, producing X-ray flares, in the same pattern as the optical bursts, just before the debris fell into the black hole.

    “In essence, this black hole has not had much to feed on for a while, and suddenly along comes an unlucky star full of matter,” says Dheeraj Pasham, the paper’s first author and a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “What we’re seeing is, this stellar material is not just continuously being fed onto the black hole, but it’s interacting with itself — stopping and going, stopping and going. This is telling us that the black hole is ‘choking’ on this sudden supply of stellar debris.”

    Pasham’s co-authors include MIT Kavli postdoc Aleksander Sadowski and researchers from NASA’s Goddard Space Flight Center, the University of Maryland, the Harvard-Smithsonian Center for Astrophysics, Columbia University, and Johns Hopkins University.

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  • richardmitnick 4:19 pm on March 8, 2017 Permalink | Reply
    Tags: , MIT, ozy.com, , Sabrina Pasterski,   

    From MIT and Harvard via ozy.com: Women in Stem “This Millennial Might Be the New Einstein” Sabrina Pasterski 

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    JAN 12 2016
    Farah Halime

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    Sabrina Pasterski

    Her research could change our understanding of the fundamentals as we know them.

    One of the things the brilliant minds at MIT do — besides ponder the nature of the universe and build sci-fi gizmos, of course — is notarize aircraft airworthiness for the federal government. So when Sabrina Pasterski walked into the campus offices one cold January morning seeking the OK for a single-engine plane she had built, it might have been business as usual. Except that the shaggy-haired, wide-eyed plane builder before them was just 14 and had already flown solo. “I couldn’t believe it,” recalls Peggy Udden, an executive secretary at MIT, “not only because she was so young, but a girl.”

    OK, it’s 2016, and gifted females are not exactly rare at MIT; nearly half the undergrads are women. But something about Pasterski led Udden not just to help get her plane approved, but to get the attention of the university’s top professors. Now, eight years later, the lanky, 22-year-old Pasterski is already an MIT graduate and Harvard Ph.D. candidate who has the world of physics abuzz. She’s exploring some of the most challenging and complex issues in physics, much as Stephen Hawking and Albert Einstein (whose theory of relativity just turned 100 years old) did early in their careers. Her research delves into black holes, the nature of gravity and spacetime. A particular focus is trying to better understand “quantum gravity,” which seeks to explain the phenomenon of gravity within the context of quantum mechanics. Discoveries in that area could dramatically change our understanding of the workings of the universe.

    She’s also caught the attention of some of America’s brightest working at NASA. Also? Jeff Bezos, founder of Amazon.com and aerospace developer and manufacturer Blue Origin, who’s promised her a job whenever she’s ready. Asked by e-mail recently whether his offer still stands, Bezos told OZY: “God, yes!”

    But unless you’re the kind of rabid physics fan who’s seen her papers on semiclassical Virasoro symmetry of the quantum gravity S-matrix and Low’s subleading soft theorem as a symmetry of QED (both on approaches to understanding the shape of space and gravity and the first two papers she ever authored), you may not have heard of Pasterski. A first-generation Cuban-American born and bred in the suburbs of Chicago, she’s not on Facebook, LinkedIn or Instagram and doesn’t own a smartphone. She does, however, regularly update a no-frills website called PhysicsGirl, which features a long catalog of achievements and proficiencies. Among them: “spotting elegance within the chaos.”

    Pasterski stands out among a growing number of newly minted physics grads in the U.S. There were 7,329 in 2013, double the four-decade low of 3,178 in 1999, according to the American Institute of Physics. Nima Arkani-Hamed, a Princeton professor and winner of the inaugural $3 million Fundamental Physics Prize, told OZY he’s heard “terrific things” about Pasterski from her adviser, Harvard professor Andrew Strominger, who is about to publish a paper with physics rock star Hawking. She’s also received hundreds of thousands of dollars in grants from the Hertz Foundation, the Smith Foundation and the National Science Foundation.

    Pasterski, who speaks in frenetic bursts, says she has always been drawn to challenging what’s possible. “Years of pushing the bounds of what I could achieve led me to physics,” she says from her dorm room at Harvard. Yet she doesn’t make it sound like work at all: She calls physics “elegant” but also full of “utility.”

    Despite her impressive résumé, MIT wait-listed Pasterski when she first applied. Professors Allen Haggerty and Earll Murman were aghast. Thanks to Udden, the pair had seen a video of Pasterski building her airplane. “Our mouths were hanging open after we looked at it,” Haggerty said. “Her potential is off the charts.” The two went to bat for her, and she was ultimately accepted, later graduating with a grade average of 5.00, the school’s highest score possible.

    An only child, Pasterski speaks with some awkwardness and punctuates her e-mails with smiley faces and exclamation marks. She says she has a handful of close friends but has never had a boyfriend, an alcoholic drink or a cigarette. Pasterski says: “I’d rather stay alert, and hopefully I’m known for what I do and not what I don’t do.”

    While mentors offer predictions of physics fame, Pasterski appears well grounded. “A theorist saying he will figure out something in particular over a long time frame almost guarantees that he will not do it,” she says. And Bezos’s pledge notwithstanding, the big picture for science grads in the U.S. is challenging: The U.S. Census Bureau’s most recent American Community Survey shows that only about 26 percent of science grads in the U.S. had jobs in their chosen fields, while nearly 30 percent of physics and chemistry post-docs are unemployed. Pasterski seems unperturbed. “Physics itself is exciting enough,” she says. ”It’s not like a 9-to-5 thing. When you’re tired you sleep, and when you’re not, you do physics.”
    ________________________________________________________________________________________________________________________________________
    Sabrina Gonzalez Pasterski (born June 3, 1993) is an American physicist from Chicago, Illinois who studies string theory and high energy physics. She describes herself as “a proud first-generation Cuban-American & Chicago Public Schools alumna.” She completed her undergraduate studies at the Massachusetts Institute of Technology (MIT) and is currently a graduate student at Harvard University.

    Pasterski has made contributions in the field of gravitational memories.[9] She is best known for her concept of “the Triangle,” which connects several physical ideas.

    Pasterski was born in Chicago on June 3, 1993. She enrolled at the Edison Regional Gifted Center in 1998, and graduated from the Illinois Mathematics and Science Academy in 2010.[10]

    Pasterski holds an active interest in aviation. She took her first flying lesson in 2003, co-piloted FAA1 at EAA AirVenture Oshkosh in 2005 and started building a kit aircraft by 2006. She soloed her Cessna 150 in Canada in 2007 and certified the aircraft she had built from a kit as airworthy in 2008, with MIT’s assistance.[citation needed] Her first U.S. solo flight was in that kit aircraft in 2009 after being signed off by her CFI Jay Maynard.[citation needed]

    Pasterski’s scientific heroes include Leon Lederman, Dudley Herschbach, and Freeman Dyson, and she was drawn to physics by Jeff Bezos. She has received job offers from Blue Origin, an aerospace company founded by Amazon.com’s Jeff Bezos, and the National Aeronautics and Space Administration (NASA).

    Before focusing on high energy theory, Pasterski worked on the CMS experiment at the Large Hadron Collider. At 21, Pasterski spoke at Harvard about her concepts of “the Triangle” and “Spin Memory”, and completed “the Triangle” for EM during an invited talk at MIT’s Center for Theoretical Physics. This work has formed the basis for further work, with one 2015 paper describing it as “a recently discovered universal triangle connecting soft theorems, symmetries and memory in gauge and gravitational theories. At 22, she spoke at a Harvard Faculty Conference about whether or not those concepts should be applied to black hole hair and discussed her new method for detecting gravitational waves.

    In early 2016, a paper by Stephen Hawking, Malcolm J. Perry, and Andrew Strominger (Pasterski’s doctoral advisor of whom she was working independently at the time) titled “Soft Hair on Black Holes” cited Pasterski’s work, making hers the only one of twelve single-author papers referenced that was authored by a female scientist.[non-primary source needed] This resulted in extensive media coverage after its appearance on the arXiv and in the days leading up to it.

    Shortly after the 2016 Hawking paper was released, actor George Takei referenced Pasterski on his Twitter account with her quote, “‘Hopefully I’m known for what I do and not what I don’t do.’ A poignant sentiment.” The Steven P. Jobs Trust article included in the tweet has been shared over 527,000 times.

    International coverage of the paper and Pasterski’s work subsequently appeared in Russia Today, Poland’s Angora newspaper and DNES in the Czech Republic. In 2016, rapper Chris Brown posted a page with a video promoting Pasterski. Forbes and The History Channel ran stories about Pasterski for their audiences in Mexico and Latin America respectively. People en Español, one of the most widely read Spanish language magazines, featured Pasterski in their April 2016 print edition. [Wikipedia]

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    The Department of Physics at Harvard is large and diverse. With 10 Nobel Prize winners (see above) to its credit, the distinguished faculty of today engages in teaching and research that spans the discipline and defines its borders, and as a result Harvard is consistently one of the top-ranked physics departments in the nation.

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  • richardmitnick 8:55 am on March 7, 2017 Permalink | Reply
    Tags: "superballistic” flow resembles the behavior of gases, , Big bunches of gas molecules or big bunches of electrons move faster than smaller numbers passing through the same bottleneck, Electrons go superballistic, MIT,   

    From MIT: “Electrons go superballistic” 

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    Physicists have long wondered why electrons sometimes move freely as superconducting materials cool and other times jam up electrical flow. Electrons’ split personalities may be the answer.
    Credit: Roman Sigaev | Shutterstock

    March 6, 2017
    David L. Chandler

    A new finding by physicists at MIT and in Israel shows that under certain specialized conditions, electrons can speed through a narrow opening in a piece of metal more easily than traditional theory says is possible.

    This “superballistic” flow resembles the behavior of gases flowing through a constricted opening, however it takes place in a quantum-mechanical electron fluid, says MIT physics professor Leonid Levitov, who is the senior author of a paper describing the finding that appears this week in the Proceedings of the National Academy of Sciences.

    In these constricted passageways, whether for gases passing through a tube or electrons moving through a section of metal that narrows to a point, it turns out that the more, the merrier: Big bunches of gas molecules, or big bunches of electrons, move faster than smaller numbers passing through the same bottleneck.

    The behavior seems paradoxical. It’s as though a mob of people trying to squeeze through a doorway all at once find that they can get through faster than one person going through alone and unobstructed. But scientists have known for nearly a century that this is exactly what happens with gases passing through a tiny opening, and the behavior can be explained through simple, basic physics, Levitov says.

    In a passageway of a given size, if there are few gas molecules, they can travel unimpeded in straight lines. This means if they are moving at random, most of them will quickly hit the wall and bounce off, losing some of their energy to the wall in the process and thus slowing down every time they hit. But with a bigger batch of molecules, most of them will bump into other molecules more often than they will hit the walls. Collisions with other molecules are “lossless,” since the total energy of the two particles that collide is preserved, and no overall slowdown occurs. “Molecules in a gas can achieve through ‘cooperation’ what they cannot accomplish individually,” he says.

    As the density of molecules in a passageway goes up, he explains, “You reach a point where the hydrodynamic pressure you need to push the gas through goes down, even though the particle density goes up.” In short, strange as it might seem, the crowding makes the molecules speed up.

    A similar phenomenon, the researchers now report, governs the behavior of electrons when they are hurtling through a narrow piece of metal, where they move in a fluid-like flow.

    The result is that, through a sufficiently narrow, point-like constriction in a metal, electrons can flow at a rate that exceeds what had been considered a fundamental limit, known as Landauer’s ballistic limit. Because of this, the team has dubbed the new effect “superballistic” flow. This represents a great drop in the electrical resistance of the metal — though it is much less of a drop than what would be required to produce the zero resistance in superconducting metals. However, unlike superconductivity, which requires extremely low temperatures, the new phenomenon may take place even at room temperature and thus may be far easier to implement for applications in electronic devices.

    In fact, the phenomenon actually increases as the temperature rises. In contrast to superconductivity, Levitov says, superballistic flow “is assisted by temperature, rather than hindered by it.”

    Through this mechanism, Levitov says, “we can overcome this boundary that everyone thought was a fundamental limit on how high the conductance could be. We’ve shown that one can do better than that.”

    He says that though this particular paper is purely theoretical, other teams have already proved its basic predictions experimentally. While the speedup observed in flowing gases in the analogous case can achieve a tenfold or greater speedup, it remains to be seen whether improvements of that magnitude can be achieved for electrical conductance. But even modest reductions in resistance in some electronic circuits could be a significant improvement, he says.

    “This work is careful, elegant, and surprising — all the hallmarks of very high-quality research,” says David Goldhaber-Gordon, a professor of physics at Stanford University who was not involved in this research. “In science, I feel phenomena that confound our intuitions are always useful in stretching our sense of what is possible. Here, the idea that more electrons can fit through an aperture if the electrons deflect each other rather than traveling freely and independently is quite counterintuitive, in fact the opposite of what we’re used to. It’s especially intriguing that Levitov and co-workers find that the conductance in such systems follows such a simple rule.”

    While this work was theoretical, Goldhaber-Gordon adds, “Testing Levitov’s simple and striking predictions experimentally will be really exciting and plausible to achieve in graphene. … Researchers have imagined building new types of electronic switches based on ballistic electron flow. Levitov’s theoretical insights, if validated experimentally, would be highly relevant to this idea: Superballistic flow could allow these switches to perform better than expected (or could show that they won’t work as hoped).”

    Haoyu Guo, the paper’s lead author, is a junior who had just arrived at MIT as a second-year transfer student from Peking University when he started the work on this project — an unusual level of achievement for an undergraduate, especially one who had just arrived on campus, Levitov says. Guo worked on the project in part through MIT’s Undergraduate Research Opportunities Program, or UROP.

    The team also included Ekin Ilseven at MIT and Gregory Falkovich, a professor of physics at the Weizmann Institute in Rehovot, Israel.

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  • richardmitnick 10:58 pm on March 3, 2017 Permalink | Reply
    Tags: , , , MIT,   

    From MIT: “MIT researchers create new form of matter” 

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    MIT Physics

    March 2, 2017
    Julia C. Keller

    1
    The Ketterle group at MIT’s Killian court. Pictured from left to right: Furkan Çağrı Top, Junru Li, Sean Burchesky, Alan O. Jamison, Wolfgang Ketterle, Boris Shteynas, Wujie Huang, and Jeongwon Lee.
    Photo courtesy of the researchers.

    2
    This image shows the equipment used by the Ketterle group to create a supersolid. Photo courtesy of the researchers.

    Supersolid is crystalline and superfluid at the same time.

    MIT physicists have created a new form of matter, a supersolid, which combines the properties of solids with those of superfluids.

    By using lasers to manipulate a superfluid gas known as a Bose-Einstein condensate, the team was able to coax the condensate into a quantum phase of matter that has a rigid structure — like a solid — and can flow without viscosity — a key characteristic of a superfluid. Studies into this apparently contradictory phase of matter could yield deeper insights into superfluids and superconductors, which are important for improvements in technologies such as superconducting magnets and sensors, as well as efficient energy transport. The researchers report their results this week in the journal Nature.

    “It is counterintuitive to have a material which combines superfluidity and solidity,” says team leader Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. “If your coffee was superfluid and you stirred it, it would continue to spin around forever.”

    Physicists had predicted the possibility of supersolids but had not observed them in the lab. They theorized that solid helium could become superfluid if helium atoms could move around in a solid crystal of helium, effectively becoming a supersolid. However, the experimental proof remained elusive.

    The team used a combination of laser cooling and evaporative cooling methods, originally co-developed by Ketterle, to cool atoms of sodium to nanokelvin temperatures. Atoms of sodium are known as bosons, for their even number of nucleons and electrons. When cooled to near absolute zero, bosons form a superfluid state of dilute gas, called a Bose-Einstein condensate, or BEC.

    Ketterle co-discovered BECs — a discovery for which he was recognized with the 2001 Nobel Prize in physics.

    “The challenge was now to add something to the BEC to make sure it developed a shape or form beyond the shape of the ‘atom trap,’ which is the defining characteristic of a solid,” explains Ketterle.

    Flipping the spin, finding the stripes

    To create the supersolid state, the team manipulated the motion of the atoms of the BEC using laser beams, introducing “spin-orbit coupling.”

    In their ultrahigh-vacuum chamber, the team used an initial set of lasers to convert half of the condensate’s atoms to a different quantum state, or spin, essentially creating a mixture of two Bose-Einstein condensates. Additional laser beams then transferred atoms between the two condensates, called a “spin flip.”

    “These extra lasers gave the ‘spin-flipped’ atoms an extra kick to realize the spin-orbit coupling,” Ketterle says.

    Physicists had predicted that a spin-orbit coupled Bose-Einstein condensate would be a supersolid due to a spontaneous “density modulation.” Like a crystalline solid, the density of a supersolid is no longer constant and instead has a ripple or wave-like pattern called the “stripe phase.”

    “The hardest part was to observe this density modulation,” says Junru Li, an MIT graduate student who worked on the discovery. This observation was accomplished with another laser, the beam of which was diffracted by the density modulation. “The recipe for the supersolid is really simple,” Li adds, “but it was a big challenge to precisely align all the laser beams and to get everything stable to observe the stripe phase.”

    Mapping out what is possible in nature

    Currently, the supersolid only exists at extremely low temperatures under ultrahigh-vacuum conditions. Going forward, the team plans to carry out further experiments on supersolids and spin-orbit coupling, characterizing and understanding the properties of the new form of matter they created.

    “With our cold atoms, we are mapping out what is possible in nature,” explains Ketterle. “Now that we have experimentally proven that the theories predicting supersolids are correct, we hope to inspire further research, possibly with unanticipated results.”

    Several research groups were working on realizing the first supersolid. In the same issue of Nature, a group in Switzerland reported an alternative way of turning a Bose-Einstein condensate into a supersolid with the help of mirrors, which collected laser light scattering by the atoms. “The simultaneous realization by two groups shows how big the interest is in this new form of matter,” says Ketterle.

    Ketterle’s team members include graduate students Junru Li, Boris Shteynas, Furkan Çağrı Top, and Wujie Huang; undergraduate Sean Burchesky; and postdocs Jeongwon Lee and Alan O. Jamison, all of whom are associates at MIT’s Research Laboratory of Electronics.

    This research was funded by the National Science Foundation, the Air Force Office for Scientific Research, and the Army Research Office.

    See the full article here .

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  • richardmitnick 6:03 pm on February 14, 2017 Permalink | Reply
    Tags: MIT, , Quantum dot spectrometer   

    From Goddard: “NASA and MIT Collaborate to Develop Space-Based Quantum-Dot Spectrometer” 

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    NASA Goddard Space Flight Center

    Feb. 14, 2017
    Lori Keesey
    lori.keesey@nasa.gov
    NASA’s Goddard Space Flight Center

    1
    Principal Investigator Mahmooda Sultana has teamed with the Massachusetts Institute of Technology to develop a quantum dot spectrometer for use in space. In this photo, she is characterizing the optical properties of the quantum dot pixels.
    Credits: NASA/W. Hrybyk

    A NASA technologist has teamed with the inventor of a new nanotechnology that could transform the way space scientists build spectrometers, the all-important device used by virtually all scientific disciplines to measure the properties of light emanating from astronomical objects, including Earth itself.

    Mahmooda Sultana, a research engineer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, now is collaborating with Moungi Bawendi, a chemistry professor at the Cambridge-based Massachusetts Institute of Technology, or MIT, to develop a prototype imaging spectrometer based on the emerging quantum-dot technology that Bawendi’s group pioneered.

    NASA’s Center Innovation Fund, which supports potentially trailblazing, high-risk technologies, is funding the effort.

    Introducing Quantum Dots

    2
    This illustration shows how a device prints the quantum dot filters that absorb different wavelengths of light depending on their size and composition. The emerging technology could give scientists a more flexible, cost-effective approach for developing spectrometers, a commonly used instrument. Credits: O’Reilly Science Art

    Quantum dots are a type of semiconductor nanocrystal discovered in the early 1980s. Invisible to the naked eye, the dots have proven in testing to absorb different wavelengths of light depending on their size, shape, and chemical composition. The technology is promising to applications that rely on the analysis of light, including smartphone cameras, medical devices, and environmental-testing equipment.

    “This is as novel as it gets,” Sultana said, referring to the technology that she believes could miniaturize and potentially revolutionize space-based spectrometers, particularly those used on uninhabited aerial vehicles and small satellites. “It really could simplify instrument integration.”

    Absorption spectrometers, as their name implies, measure the absorption of light as a function of frequency or wavelength due to its interaction with a sample, such as atmospheric gases.

    After passing through or interacting with the sample, the light reaches the spectrometer. Traditional spectrometers use gratings, prisms, or interference filters to split the light into its component wavelengths, which their detector pixels then detect to produce spectra. The more intense the absorption in the spectra, the greater the presence of a specific chemical.

    While space-based spectrometers are getting smaller due to miniaturization, they still are relatively large, Sultana said. “Higher-spectral resolution requires long optical paths for instruments that use gratings and prisms. This often results in large instruments. Whereas here, with quantum dots that act like filters that absorb different wavelengths depending on their size and shape, we can make an ultra-compact instrument. In other words, you could eliminate optical parts, like gratings, prisms, and interference filters.”

    Just as important, the technology allows the instrument developer to generate nearly an unlimited number of different dots. As their size decreases, the wavelength of the light that the quantum dots will absorb decreases. “This makes it possible to produce a continuously tunable, yet distinct, set of absorptive filters where each pixel is made of a quantum dot of a specific size, shape, or composition. We would have precise control over what each dot absorbs. We could literally customize the instrument to observe many different bands with high-spectral resolution.”

    Prototype Instrument Under Development

    With her NASA technology-development support, Sultana is working to develop, qualify through thermal vacuum and vibration tests, and demonstrate a 20-by-20 quantum-dot array sensitive to visible wavelengths needed to image the sun and the aurora. However, the technology easily can be expanded to cover a broader range of wavelengths, from ultraviolet to mid-infrared, which may find many potential space applications in Earth science, heliophysics, and planetary science, she said.

    Under the collaboration, Sultana is developing an instrument concept particularly for a CubeSat application and MIT doctoral student Jason Yoo is investigating techniques for synthesizing different precursor chemicals to create the dots and then printing them onto a suitable substrate. “Ultimately, we would want to print the dots directly onto the detector pixels,” she said.

    “This is a very innovative technology,” Sultana added, conceding that it is very early in its development. “But we’re trying to raise its technology-readiness level very quickly. Several space-science opportunities that could benefit are in the pipeline.”

    For more Goddard technology news, go to: http://gsfctechnology.gsfc.nasa.gov/newsletter/Current.pdf

    See the full article here.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

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  • richardmitnick 2:57 pm on February 10, 2017 Permalink | Reply
    Tags: MIT, Scientists estimate solar nebula’s lifetime   

    From MIT: “Scientists estimate solar nebula’s lifetime” 

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    February 9, 2017
    Jennifer Chu

    1
    By studying the remanent magnetizations in ancient meteorites, an MIT team has determined that the solar nebula — the vast of disc of gas and dust that ultimately gave rise to the solar system — lasted around 3 to 4 million years.
    Image: Hernan Canellas

    About 4.6 billion years ago, an enormous cloud of hydrogen gas and dust collapsed under its own weight, eventually flattening into a disk called the solar nebula. Most of this interstellar material contracted at the disk’s center to form the sun, and part of the solar nebula’s remaining gas and dust condensed to form the planets and the rest of our solar system.

    Now scientists from MIT and their colleagues have estimated the lifetime of the solar nebula — a key stage during which much of the solar system evolution took shape.

    This new estimate suggests that the gas giants Jupiter and Saturn must have formed within the first 4 million years of the solar system’s formation. Furthermore, they must have completed gas-driven migration of their orbital positions by this time.

    “So much happens right at the beginning of the solar system’s history,” says Benjamin Weiss, professor of earth, atmospheric, and planetary sciences at MIT. “Of course the planets evolve after that, but the large-scale structure of the solar system was essentially established in the first 4 million years.”

    Weiss and MIT postdoc Huapei Wang, the first author of this study, report their results today in the journal Science. Their co-authors are Brynna Downey, Clement Suavet, and Roger Fu from MIT; Xue-Ning Bai of the Harvard-Smithsonian Center for Astrophysics; Jun Wang and Jiajun Wang of Brookhaven National Laboratory; and Maria Zucolotto of the National Museum in Rio de Janeiro.

    Spectacular recorders

    By studying the magnetic orientations in pristine samples of ancient meteorites that formed 4.653 billion years ago, the team determined that the solar nebula lasted around 3 to 4 million years. This is a more precise figure than previous estimates, which placed the solar nebula’s lifetime at somewhere between 1 and 10 million years.

    The team came to its conclusion after carefully analyzing angrites, which are some of the oldest and most pristine of planetary rocks. Angrites are igneous rocks, many of which are thought to have erupted onto the surface of asteroids very early in the solar system’s history and then quickly cooled, freezing their original properties — including their composition and paleomagnetic signals — in place.

    Scientists view angrites as exceptional recorders of the early solar system, particularly as the rocks also contain high amounts of uranium, which they can use to precisely determine their age.

    “Angrites are really spectacular,” Weiss says. “Many of them look like what might be erupting on Hawaii, but they cooled on a very early planetesimal.”

    Weiss and his colleagues analyzed four angrites that fell to Earth at different places and times.

    “One fell in Argentina, and was discovered when a farm worker was tilling his field,” Weiss says. “It looked like an Indian artifact or bowl, and the landowner kept it by this house for about 20 years, until he finally decided to have it analyzed, and it turned out to be a really rare meteorite.”

    The other three meteorites were discovered in Brazil, Antarctica, and the Sahara Desert. All four meteorites were remarkably well-preserved, having undergone no additional heating or major compositional changes since they originally formed.

    Measuring tiny compasses

    The team obtained samples from all four meteorites. By measuring the ratio of uranium to lead in each sample, previous studies had determined that the three oldest formed around 4.653 billion years ago. The researchers then measured the rocks’ remnant magnetization using a precision magnetometer in the MIT Paleomagnetism Laboratory.

    “Electrons are little compass needles, and if you align a bunch of them in a rock, the rock becomes magnetized,” Weiss explains. “Once they’re aligned, which can happen when a rock cools in the presence of a magnetic field, then they stay that way. That’s what we use as records of ancient magnetic fields.”

    When they placed the angrites in the magnetometer, the researchers observed very little remnant magnetization, indicating there was very little magnetic field present when the angrites formed.

    The team went a step further and tried to reconstruct the magnetic field that would have produced the rocks’ alignments, or lack thereof. To do so, they heated the samples up, then cooled them down again in a laboratory-controlled magnetic field.

    “We can keep lowering the lab field and can reproduce what’s in the sample,” Weiss says. “We find only very weak lab fields are allowed, given how little remnant magnetization is in these three angrites.”

    Specifically, the team found that the angrites’ remnant magnetization could have been produced by an extremely weak magnetic field of no more than 0.6 microteslas, 4.653 billion years ago, or, about 4 million years after the start of the solar system.

    In 2014, Weiss’ group analyzed other ancient meteorites that formed within the solar system’s first 2 to 3 million years, and found evidence of a magnetic field that was about 10-100 times stronger — about 5-50 microtesla.

    “It’s predicted that once the magnetic field drops by a factor of 10-100 in the inner solar system, which we’ve now shown, the solar nebula goes away really quickly, within 100,000 years,” Weiss says. “So even if the solar nebula hadn’t disappeared by 4 million years, it was basically on its way out.”

    The planets align

    The researchers’ new estimate is much more precise than previous estimates, which were based on observations of faraway stars.

    “What’s more, the angrites’ paleomagnetism constrains the lifetime of our own solar nebula, while astronomical observations obviously measure other faraway solar systems,” Wang adds. “Since the solar nebula lifetime critically affects the final positions of Jupiter and Saturn, it also affects the later formation of the Earth, our home, as well as the formation of other terrestrial planets.”

    Now that the scientists have a better idea of how long the solar nebula persisted, they can also narrow in on how giant planets such as Jupiter and Saturn formed. Giant planets are mostly made of gas and ice, and there are two prevailing hypotheses for how all this material came together as a planet. One suggests that giant planets formed from the gravitational collapse of condensing gas, like the sun did. The other suggests they arose in a two-stage process called core accretion, in which bits of material smashed and fused together to form bigger rocky, icy bodies. Once these bodies were massive enough, they could have created a gravitational force that attracted huge amounts of gas to ultimately form a giant planet.

    According to previous predictions, giant planets that form through gravitational collapse of gas should complete their general formation within 100,000 years. Core accretion, in contrast, is typically thought to take much longer, on the order of 1 to several million years. Weiss says that if the solar nebula was around in the first 4 million years of solar system formation, this would give support to the core accretion scenario, which is generally favored among scientists.

    “The gas giants must have formed by 4 million years after the formation of the solar system,” Weiss says. “Planets were moving all over the place, in and out over large distances, and all this motion is thought to have been driven by gravitational forces from the gas. We’re saying all this happened in the first 4 million years.”

    This research was supported, in part, by NASA and a generous gift from Thomas J. Peterson, Jr.

    See the full article here .

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  • richardmitnick 2:39 pm on January 27, 2017 Permalink | Reply
    Tags: , Carbon nanotube “stitches” strengthen composites, MIT,   

    From MIT: “Carbon nanotube “stitches” strengthen composites” 

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    August 2, 2016 [Where has this been?]
    Jennifer Chu

    1
    MIT aerospace engineers have found a way to bond composite layers, producing a material that is substantially stronger and more resistant to damage than other advanced composites. The improvement may lead to stronger, lighter airplane parts. Illustration: Christine Daniloff/MIT

    The newest Airbus and Boeing passenger jets flying today are made primarily from advanced composite materials such as carbon fiber reinforced plastic — extremely light, durable materials that reduce the overall weight of the plane by as much as 20 percent compared to aluminum-bodied planes. Such lightweight airframes translate directly to fuel savings, which is a major point in advanced composites’ favor.

    But composite materials are also surprisingly vulnerable: While aluminum can withstand relatively large impacts before cracking, the many layers in composites can break apart due to relatively small impacts — a drawback that is considered the material’s Achilles’ heel.

    Now MIT aerospace engineers have found a way to bond composite layers in such a way that the resulting material is substantially stronger and more resistant to damage than other advanced composites. Their results are published this week in the journal Composites Science and Technology.

    The researchers fastened the layers of composite materials together using carbon nanotubes — atom-thin rolls of carbon that, despite their microscopic stature, are incredibly strong. They embedded tiny “forests” of carbon nanotubes within a glue-like polymer matrix, then pressed the matrix between layers of carbon fiber composites. The nanotubes, resembling tiny, vertically-aligned stitches, worked themselves within the crevices of each composite layer, serving as a scaffold to hold the layers together.

    In experiments to test the material’s strength, the team found that, compared with existing composite materials, the stitched composites were 30 percent stronger, withstanding greater forces before breaking apart.

    Roberto Guzman, who led the work as an MIT postdoc in the Department of Aeronautics and Astronautics (AeroAstro), says the improvement may lead to stronger, lighter airplane parts — particularly those that require nails or bolts, which can crack conventional composites.

    “More work needs to be done, but we are really positive that this will lead to stronger, lighter planes,” says Guzman, who is now a researcher at the IMDEA Materials Institute, in Spain. “That means a lot of fuel saved, which is great for the environment and for our pockets.”

    The study’s co-authors include AeroAstro professor Brian Wardle and researchers from the Swedish aerospace and defense company Saab AB.

    “Size matters”

    Today’s composite materials are composed of layers, or plies, of horizontal carbon fibers, held together by a polymer glue, which Wardle describes as “a very, very weak, problematic area.” Attempts to strengthen this glue region include Z-pinning and 3-D weaving — methods that involve pinning or weaving bundles of carbon fibers through composite layers, similar to pushing nails through plywood, or thread through fabric.

    “A stitch or nail is thousands of times bigger than carbon fibers,” Wardle says. “So when you drive them through the composite, you break thousands of carbon fibers and damage the composite.”

    Carbon nanotubes, by contrast, are about 10 nanometers in diameter — nearly a million times smaller than the carbon fibers.

    “Size matters, because we’re able to put these nanotubes in without disturbing the larger carbon fibers, and that’s what maintains the composite’s strength,” Wardle says. “What helps us enhance strength is that carbon nanotubes have 1,000 times more surface area than carbon fibers, which lets them bond better with the polymer matrix.”

    Stacking up the competition

    Guzman and Wardle came up with a technique to integrate a scaffold of carbon nanotubes within the polymer glue. They first grew a forest of vertically-aligned carbon nanotubes, following a procedure that Wardle’s group previously developed. They then transferred the forest onto a sticky, uncured composite layer and repeated the process to generate a stack of 16 composite plies — a typical composite laminate makeup — with carbon nanotubes glued between each layer.

    To test the material’s strength, the team performed a tension-bearing test — a standard test used to size aerospace parts — where the researchers put a bolt through a hole in the composite, then ripped it out. While existing composites typically break under such tension, the team found the stitched composites were stronger, able to withstand 30 percent more force before cracking.

    The researchers also performed an open-hole compression test, applying force to squeeze the bolt hole shut. In that case, the stitched composite withstood 14 percent more force before breaking, compared to existing composites.

    “The strength enhancements suggest this material will be more resistant to any type of damaging events or features,” Wardle says. “And since the majority of the newest planes are more than 50 percent composite by weight, improving these state-of-the art composites has very positive implications for aircraft structural performance.”

    Stephen Tsai, emeritus professor of aeronautics and astronautics at Stanford University, says advanced composites are unmatched in their ability to reduce fuel costs, and therefore, airplane emissions.

    “With their intrinsically light weight, there is nothing on the horizon that can compete with composite materials to reduce pollution for commercial and military aircraft,” says Tsai, who did not contribute to the study. But he says the aerospace industry has refrained from wider use of these materials, primarily because of a “lack of confidence in [the materials’] damage tolerance. The work by Professor Wardle addresses directly how damage tolerance can be improved, and thus how higher utilization of the intrinsically unmatched performance of composite materials can be realized.”

    This work was supported by Airbus Group, Boeing, Embraer, Lockheed Martin, Saab AB, Spirit AeroSystems Inc., Textron Systems, ANSYS, Hexcel, and TohoTenax through MIT’s Nano-Engineered Composite aerospace STructures (NECST) Consortium and, in part, by the U.S. Army.

    See the full article here .

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  • richardmitnick 10:46 am on January 5, 2017 Permalink | Reply
    Tags: , , , , MIT, , The Search for Extraterrestrial Genomes or SETG   

    From Many Worlds: “In Search of Panspermia” 

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    Many Worlds

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    2017-01-05
    Marc Kaufman

    1
    This image is from the NASA Remote Sensing Tutorial. NASA

    When scientists approach the question of how life began on Earth, or elsewhere, their efforts generally involve attempts to understand how non-biological molecules bonded, became increasingly complex, and eventually reached the point where they could replicate or could use sources of energy to make things happen. Ultimately, of course, life needed both.

    Researchers have been working for some time to understand this very long and winding process, and some have sought to make synthetic life out of selected components and energy. Some startling progress has been made in both of these endeavors, but many unexplained mysteries remain at the heart of the processes. And nobody is expecting the origin of life on Earth (or elsewhere) to be fully understood anytime soon.

    To further complicate the picture, the history of early Earth is one of extreme heat caused by meteorite bombardment and, most important, the enormous impact some 4.5 billion years of the Mars-sized planet that became our moon. As a result, many early Earth researchers think the planet was uninhabitable until about 4 billion years ago.

    Yet some argue that signs of Earth life 3.8 billion years ago have been detected in the rock record, and lifeforms were certainly present 3.5 billion years ago. Considering the painfully slow pace of early evolution — the planet, after all, supported only single-cell life for several billion years before multicellular life emerged — some researchers are skeptical about the likelihood of DNA-based life evolving in the relatively short window between when Earth became cool enough to support life and the earliest evidence of actual life.

    1
    A DNA helix animation. Life on Earth is based on DNA, and some researchers have been working on ways to determine whether DNA life also exists on Mars or elsewhere in the solar system. No image credit.

    So what else, from a scientific as opposed to a religious perspective, might have set into motion the process that made life out of non-life?

    A team of prominent scientists at MIT and Harvard are sufficiently convinced in the plausibility of panspermia that they have spent a decade, and a fair amount of NASA and other funding, to design and produce an instrument that can be sent to Mars and potentially detect DNA or more primitive RNA.

    In other words, life not only similar to that on Earth, but actually delivered long ago from Earth. It’s called the The Search for Extraterrestrial Genomes, or SETG.

    Gary Ruvkun is one of those researchers, a pioneering molecular biologist at Massachusetts General Hospital and professor of genetics at Harvard Medical School.

    I heard him speaking recently at a Space Sciences Board workshop on biosignatures, where he described the real (if slim) possibility that DNA or RNA-based life exists now on Mars, and the instrument that the SETG group is developing to detect it should it be there.

    The logic of panspermia — or perhaps “dispermia” if between but two planets — is pretty straight-forward, though with some significant question marks. Both Earth and Mars, it is well known, were pummeled by incoming meteorites in their earlier epochs, and those impacts are known to have sufficient force to send rock from the crash site into orbit.

    Mars meteorites have been found on Earth, and Earth meteorites no doubt have landed on Mars. Ruvkun said that recent work on the capacity of dormant microbes to survive the long, frigid and irradiated trip from planet to planet has been increasingly supportive.

    “Earth is filled with life in every nook and cranny, and that life is wildly diverse,” he told the workshop. “So if you’re looking for life on Mars, surely the first thing to look for is life like we find on Earth. Frankly, it would be kind of stupid not to.”

    The instrument being developed by the group, which is led by Ruvkun and Maria Zuber, MIT vice president for research and head of the Department of Earth, Atmospheric and Planetary Sciences. It would potentially be part of a lander or rover science package and would search DNA or RNA, using techniques based on the exploding knowledge of earthly genomics.

    The job is made easier, Ruvkun said, by the fact that the basic structure of DNA is the same throughout biology. What’s more, he said, there about 400 specific genes sequences “that make up the core of biology — they’re found in everything from extremeophiles and bacteria to worms and humans.”

    Those ubiquitous gene sequences, he said, were present more than 3 billion years ago in seemingly primitive lifeforms that were, in fact, not primitive at all. Rather, they had perfected some genetic pathways that were so good that they still used by most everything alive today.

    And how was it that these sophisticated life processes emerged not all that long (in astronomical or geological terms) after Earth cooled enough to be habitable? “Either life developed here super-fast or it came full-on as DNA life from afar,” Ruvkun said. It’s pretty clear which option he supports.

    Ruvkun said that the rest of the SETG team sees that kind of inter-planetary transfer — to Mars and from Mars — as entirely plausible, and that he takes panspermia a step forward. He thinks it’s possible, though certainly not likely nor remotely provable today, that life has been around in the cosmos for as long as 10 billion years, jumping from one solar system and planet to another. Not likely, but at idea worth entertaining.

    Maria Zuber of MIT, who was the PI for the recent NASA GRAIL mission to the moon, has been part of the SETG team since near its inception, and MIT research scientist Christopher Carr is the project manager. Zuber said it was a rather low-profile effort at the start, but over the years has attracted many students and has won NASA funding three times including the currently running Maturation of Instruments for Solar System Exploration (MatISSE) grant.

    “I have made my career out of doing simple experiments. if want to look for life beyond earth helps to know what you’re looking for.

    “We happen to know what life on Earth is like– DNA based or possibly RNA-based as Gary is looking for as well. The point is that we know what to look for. There are so many possibilities of what life beyond Earth could be like that we might as well test the hypothesis that it, also, is DNA based. It’s a low probability result, but potentially very high value.”

    DNA sequencing instruments like the one her team is developing are taken to the field regularly by thousands of researchers, including some working with with SETG. The technology has advanced so quickly that they can pick up a sample in a marsh or desert or any extreme locale and on the spot determine what DNA is present. That’s quite a change from the pain-staking sequencing done painstakingly by graduate students not that long ago.

    Panspermia, Zuber acknowledged, is a rather improbable idea. But when nature is concerned, she said “I’m reticent to say anything is impossible. After all, the universe is made up of the same elements as those on Earth, and so there’s a basic commonality.”

    Zuber said the instrument was not ready to compete for a spot on the 2020 mission to Mars, but she expects to have a sufficiently developed one ready to compete for a spot on the next Mars mission. Or perhaps on missions to Europa or the plumes of Enceladus.

    he possibility of life skipping from planet to planet clearly fascinates both scientists and the public. You may recall the excitement in the mid 1990s over the Martian meteorite ALH84001, which NASA researchers concluded contained remnants of Martian life. (That claim has since been largely refuted.)

    Of the roughly 61,000 meteorites found on Earth, only 134 were deemed to be Martian as of two years ago. But how many have sunk into oceans or lakes, or been lost in the omnipresence of life on Earth? Not surprisingly, the two spots that have yielded the most meteorites from Mars are Antarctica and the deserts of north Africa.

    And when thinking of panspermia, it’s worthwhile to consider the enormous amount of money and time put into keeping Earthly microbes from inadvertently hitching a ride to Mars or other planets and moons as part of a NASA mission.

    The NASA office of planetary protection has the goal of ensuring, as much as possible, that other celestial bodies don’t get contaminated with our biology. Inherent in that concern is the conclusion that our microbes could survive in deep space, could survive the scalding entry to another planet, and could possibly survive on the planet’s surface today. In other words, that panspermia (or dispermia) is in some circumstances possible.

    Testing whether a spacecraft has brought Earth life to Mars is actually another role that the SETG instrument could play. If a sample tested on Mars comes back with a DNA signature result exactly like one on Earth–rather one that might have come initially from Earth and then evolved over billions of years– then scientists will know that particular bit of biology was indeed a stowaway from Earth.

    Rather like how a very hardy microbe inside a meteorite might have possibly traveled long ago.

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
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